Season Extension and Weed Management: High Tunnels and Biodegradable Mulches Carol Miles, Vegetable Specialist Jeremy Cowan, Ph.D. Student Department of Horticulture WSU Mount Vernon NWREC

Biodegradable Mulches for Specialty Crops Produced Under Protective Covers Debra Inglis and Carol Miles (Project Directors) 1 ; Andrew Corbin, Jessica Goldberger, Karen Leonas, Tom Marsh and Tom Walters 1 ; Doug Hayes, Jaehoon Lee, Larry Wadsworth and Annette Wszelaki 2 ; Jennifer Moore-Kucera 3 ; Russ Wallace 4 ; Marion Brodhagen 5 ; and Eric Belasco 6 ; SCRI Grant Award No

SCRI Project Goals for High Tunnels  Assess agricultural and economic impacts of using high tunnels as compared to open field for tomato, lettuce and strawberry production  Compare performance of biodegradable mulch (BDM) in high tunnel and open field  Compare high tunnel structures in three diverse locations in the U.S. with focus on wind tolerance and labor requirements Nanjing Agricultural University, Nov 11

Definitions Degrade Measurable conversion of C to CO2 through abiotic factors such as heat, UV light, or mechanical stress. Biodegrade Break down via microbial activity; ultimately the oxidation of the parent compound to carbon dioxide and water, providing carbon and energy for the growth and reproduction of cells. Deteriorate Loss of physical or mechanical strength as observed through physical testing, microscopic imaging or visual assessment.

Field Experiments Variety trials: 6 cvs tomato; 6 cvs lettuce; 6 cvs strawberry BDM trial: with tomato cv. Celebrity Locations: Mount Vernon WA, Lubbock TX, Knoxville TN Experimental design: Randomized complete block with four replications Main plot: high tunnel and open field Subplots: 3 feet wide bed, 14 feet long BDM planted with tomato Plots managed organically BDM experimental treatments: 1) Experimental fabric – SB-PLA 2) BioBag – starch-based (Mater-bi®) film 3) BioTelo – starch-based (Mater-bi®) film 4) Sunshine paper – cellulose, 100% degradable 5) Standard black plastic – PE, 1.0 mil embossed 6) Bare ground / non-mulch control

High tunnels provide: Increased heat Protection from rainfall Reduced leaf wetness Increased crop yield Shortened time to harvest for many crops Mount Vernon, WA Lubbock. TX Knoxville, TN

Mount Vernon, WALubbock, TXKnoxville, TN HTOFHTOFHTOF GDD y (base 10 o C) Ave. daily max. air temp. ( o C) Ave. daily min. air temp. ( o C) Ave. soil temp at 5 cm depth BioBag BioTelo SB-PLA Weed Guard Plus Black Plastic Bare Ground Ave. sol. rad. (µmol·m -2 ·s- 1 ) Relative Humidity (%) Ave. wind speed (km·h -1 ) Total rainfall (mm)0235.5NA Climate Comparison for HT and OF

Tomato Yield High Tunnel and Open Field at Mount Vernon 2011 Total Number (plot -1 )Total Weight (kg. plot -1 )

Lettuce Yield High Tunnel and Open Field at Mount Vernon in 2011 Total Weight (kg. plot -1 )Marketable Weight (kg. plot -1 )

Plastic mulch provides: Weed control Conservation of soil moisture Increased crop yield Modified soil temperature Shortened time to harvest for many crops

Plastic mulch must be removed from the field for disposal; in-field incorporation and biodegradation would eliminate disposal costs Rick Boydston, USDA ARS

Biodegradable mulch generally made from: Poly(lactic) acid (PLA) - plant-based polyester produced from starch Polyhydroxyalkanoates (PHA) -polyesters produced by bacterial fermentation of sugar or lipids Skeletal formula of poly(lactic) acid Bacillus subtilis poly-(R)-3-hydroxybutyrate Andrew Corbin, WSU Extension

Presumed Mulch (Bio)Degradation Doug Hayes, UTK

SCRI Project Goals for Biodegradable Mulches  Assess agricultural, ecological, and economic consequences of using biodegradable mulches in high tunnels and open field  Test PLA-based spunbond as mulch prototype  Compare PLA and commercial “biodegradable” mulches for performance in growing tomatoes  Provide data that may be useful for developing an ASTM standard for biodegradation of mulches in soil Nanjing Agricultural University, Nov 11

Collaborators Nature Works (U.S.), Saxon Textile Research Institute (Germany), and GreenBio (China) Experimental PLA mulch for field testing SB-PLA-10 high MW, white SB-PLA-11 half MW of (10), small fiber size, black SB-PLA-12 blended with PHA (20%), black SCRI Project Experimental BDM

September 23, 2010 Mount Vernon Open field High tunnel

Weed Control with Biodegradable Mulch High Tunnel and Open Field, Mount Vernon 2010 Total Number (plot -1 )Total Weight (g. plot -1 )

Tomato Yield with Biodegradable Mulch High Tunnel and Open Field, Mount Vernon 2011 Total Number of Fruit (plot -1 )Total Weight of Fruit (kg. plot -1 )

Mean Tomato Fruit Quality with Mulches High Tunnel and Open Field, Mount Vernon 2011 Supported by CSANR BIOAg grant Fruit o Brix Fruit % Acidity

Mulch Visual Evaluations Two times each month measure: Number of rips, tears and holes (RTH) Percent visual deterioration (PVD) BioBag: 6/17/11 8/1/11 9/2/11 10/10/11

BDM Percent Visual Deterioration High Tunnel and Open Field 2010 Mount Vernon and Knoxville

Mulch - Laboratory Testing First Flower SB-PLA-10SB-PLA-11

BDM Sample Preparation First Flower BioTelo BioBag

BDM Sample Degradation Planting Final Harvest BioBagBioTelo Karen Leonas, WSU

BDM % Maximum Load at Final Harvest 2010 HT and OF at Mount Vernon, Lubbock & Knoxville Open Field High Tunnel Doug Hayes, UTK

Mesh Bag Study Mount Vernon 2011 Oct 2010 BB TX Mar 2011BT TX Mar 2011 Jennifer Moore-Kucera, TTU

Current Status  Year 2 field studies complete; data are being entered and analyzed  Year 1 and Year 2 preliminary reports posted on Team website  Year 1 results are being submitted for publication Winter 2011  Developed a team website and public website for information sharing